AC square-wave, sawtooth-wave, and triangle-wave fields driven adiabatic quantum pumps in nanowire structures

A dc current can be pumped through a nanostructure by two out-of-phase ac driving fields. In this approach, we explore the pumped current properties driven by square-wave, sawtooth-wave, and triangle-wave ac fields in nanowire structures by Fourier expansion. The theory can be applied to arbitrary driving fields. It is found that the pumped current varies with the phase difference as square-wave and sawtooth-wave functions, respectively, under corresponding driven fields. The sinusoidal relation governs in the pump driven by triangle-wave oscillation. Devices based on square-wave driven quantum pumps may have potential applications in digital information at nanoscale dimensions.